JP5711932B2 - Method for manufacturing device with protective cover - Google Patents

Description

  The present invention relates to a method for manufacturing a device with a protective cover in which a protective cover is disposed on the device.

  For example, in a manufacturing process of a MEMS device such as an acceleration sensor or a pressure sensor, a device wafer in which the MEMS device is arranged in each region partitioned by a plurality of division lines formed on the wafer is formed. Thereafter, each MEMS device is manufactured by cutting and dividing the device wafer along the planned division line with, for example, a cutting apparatus disclosed in Patent Document 1.

  Many MEMS devices are provided with a protective cover called a cap that protects the MEMS structure. The protective cover covers the device surface with the bonding pads disposed on the MEMS device exposed, and protects the MEMS structure.

  Conventionally, a MEMS device provided with such a protective cover has been manufactured by the following method. First, a through hole corresponding to a bonding pad of a device wafer is formed in the wafer by etching to form a protective cover wafer. Next, after aligning and bonding the through hole of the protective cover wafer and the bonding pad of the device wafer, the bonded wafer is divided along the planned dividing line to manufacture the MEMS device.

JP 2008-307646 A

  However, forming a through hole in a wafer by etching has a problem that it takes time, and management such as storing and discarding an etchant is troublesome. Furthermore, in recent years, MEMS devices have also been miniaturized, and the number of devices formed per device wafer is increasing. On the other hand, since the area and number required for the bonding pad do not change, a large number of through holes are formed in the protective cover wafer, and the ratio of the through holes in one protective cover wafer tends to increase. As a result, there is a problem that the strength of the protective cover wafer is reduced, and the protective cover wafer is damaged during handling, such as during transportation or pasting.

  This invention is made | formed in view of the said fact, The objective is to provide the manufacturing method of the device with a protective cover which manufactures the device with a protective cover easily, without damaging a protective cover wafer.

The present invention is a method for manufacturing a device with a protective cover, and includes the following steps.
(1) A device wafer preparation step of preparing a device wafer in which a device including a bonding pad formed adjacent to a division line is formed in each region divided by a plurality of intersecting division lines.
(2) a protective cover wafer groove processing step for processing the protective cover wafer by forming a groove with a cutting blade in a region on the protective cover wafer corresponding to a region on the device center side adjacent to the bonding pad on the surface of the device wafer;
(3) before or after performing the protective cover wafer groove processing step, the protective cover wafer grinding step for grinding the center of the back surface of the protective cover wafer to form a concave portion and forming an annular convex portion surrounding the concave portion;
(4) Affixing the wafer to the device center side of the bonding pad of the device wafer, and bonding the surface of the device wafer where the device is formed and the surface of the protective cover where the groove is formed to form a bonded wafer Alignment step,
(5) Bonding pad exposure step of cutting the protective cover wafer of the bonded wafer along the groove with a cutting blade to expose the bonding pad;
(6) A dividing step of dividing the bonded wafer along the division line before or after the bonding pad exposing step.

  In the present invention, since the bonding pad can be exposed from the protective cover without etching, the troublesomeness such as the management of the etchant is eliminated. Moreover, since the strength of the protective cover wafer can be increased by forming a concave portion on the back surface of the protective cover wafer and forming the concave portion surrounded by the annular convex portion, the ratio of the through holes in the protective cover is increased. However, damage to the protective cover wafer can be prevented, and the protective cover wafer can be thinned.

It is a perspective view which shows the 1st example of a device wafer. It is a perspective view which shows the state which forms a groove | channel in a protective cover wafer. It is a perspective view which shows the 1st example of the protective cover wafer in which the groove | channel was formed. It is sectional drawing which shows the state which bonded the device wafer of the 1st example to the protective cover wafer of the 1st example. It is a perspective view which shows the state which forms a recessed part in the back surface of the protective cover wafer of a 1st example. It is a perspective view which shows the protective cover wafer of the 1st example in which the recessed part was formed in the back surface. It is a perspective view which shows the state which bonds the protective cover wafer of a 1st example to the device wafer of a 1st example. It is sectional drawing which shows the state which cuts the protective cover wafer of a 1st example, and exposes a bonding pad. It is sectional drawing which shows the state which divides a bonded wafer. It is a top view which shows the 2nd example of a device wafer. It is a top view which shows the 2nd example of the protective cover wafer in which the groove | channel was formed. It is a perspective view which shows the 2nd example of the protective cover wafer in which the groove | channel was formed. It is sectional drawing which shows the state which bonded the device wafer of the 2nd example to the protective cover wafer of the 2nd example. It is sectional drawing which shows the state which cuts the protective cover wafer of a 2nd example, and exposes a bonding pad. It is sectional drawing which shows the state which divides a bonded wafer.

1 First Embodiment (1) Device Wafer Preparation Step First, a device wafer 1 shown in FIG. 1 is prepared. A device 12 is formed on the surface 10 of the device wafer 1 in a region defined by a plurality of intersecting division lines 11. The device 12 has a MEMS structure. A notch 14 that is a crystal orientation identification mark is formed at the peripheral edge of the device 12.

  As shown in an enlarged manner in FIG. 1, each device 12 has a bonding pad 13 formed so as to protrude to the surface side. In the device wafer 1, bonding pads 13 aligned along the planned division line 11 are formed on both sides of the planned division line 11 in one direction (lateral direction in the drawing). The bonding pad 13 shown in FIG. 1 forms bonding pad rows 13a and 13b for each row arranged in one direction.

(2) Protection cover wafer groove processing step As shown in FIG. 2, the back surface 21 of the protection cover wafer 2 for protecting each device 12 of the device wafer 1 is adhered to the tape T, and the surface 20 is exposed. To do. A frame F formed in a ring shape is adhered to the peripheral edge of the tape T, and the protective cover wafer 2 is supported integrally with the frame F via the tape T. On the peripheral edge of the protective cover wafer 2, a positioning mark 23 is formed in a cutout state.

  The surface 20 of the protective cover wafer 2 is located at a position not corresponding to the bonding pad 13 of the device wafer 1 when the surface 20 faces the surface 10 of the device wafer 1, specifically, the bonding pad 13 of the device wafer 1. A groove is formed by cutting using a cutting means 3 in a region on the protective cover wafer 2 corresponding to a device central side region adjacent to the surface, and the surface 20 is processed.

  The protective cover wafer 2 supported by the frame F via the tape T is held by holding means (not shown) and can move in the X direction. On the other hand, the cutting means 3 is configured such that a cutting blade 31 is attached to a tip portion of a spindle 30 having an axis in the Y direction and is fixed by a nut 32.

  The protective cover wafer 2 supported by the frame F is moved in the X direction, and the cutting means 3 is lowered while rotating the cutting blade 31 to form grooves 22 a on the surface 20 of the protective cover wafer 2. After forming one groove 22a, the cutting means 3 is fed a predetermined distance in the Y direction, and the groove 22b is formed by the same cutting. After forming the pair of grooves 22a and 22b in this manner, the cutting means 3 is fed in the Y direction, the groove 22a is formed, and the cutting means 3 is further fed in the Y direction for a predetermined distance, and the groove 22b is formed by the same cutting. Such cutting is repeated to sequentially form grooves 22a and 22b facing the device center side of all the bonding pad rows 13a and 13b of the device wafer 1 as shown in FIG. A specific example of the formation position of the groove 22 is shown below.

  As shown in FIG. 4, when the surface 20 of the protective cover wafer 2 faces the surface 10 of the device wafer 1, two bonding pad rows 13 a formed adjacent to both sides of the planned division line 11, A pair of grooves 22a and 22b are formed at positions shifted from the top of each bonding pad 13 constituting 13b toward the center of the device region 12.

(3) Protective cover wafer grinding step Before or after performing the protective cover wafer groove processing step, the center of the back surface of the protective cover wafer 2 is ground. For this grinding, for example, a grinding device 4 shown in FIG. 5 is used. The grinding apparatus 4 includes a holding table 40 that can rotate while holding the protective cover wafer 2, and a grinding means 41 that performs grinding on the protective cover wafer 2. The grinding means 41 can be moved up and down in the vertical direction as a whole, and has a rotating shaft 410 having a vertical axis, a wheel 411 mounted on the lower end of the rotating shaft 410, and an annular shape on the lower surface of the wheel 411. The grinding wheel 412 is fixed.

  In the holding table 40, the front surface 20 side of the protective cover wafer 2 is held by the holding table 40 and the back surface 21 is exposed. Then, while rotating the holding table 40 in the direction of arrow A, the grinding means 41 is lowered while rotating the rotating shaft 410 in the direction of arrow B, and the rotating grinding wheel 412 is brought into contact with the back surface 21 of the protective cover wafer 2. To grind. At this time, the concave portion 210 is formed in the central portion by grinding only the central portion, not the entire back surface 21, and the annular convex portion 211 that maintains the original thickness without being ground is formed around it, As shown in FIG. 6, the concave portion 210 is surrounded by the annular convex portion 211. Thus, the entire surface of the back surface 21 is not ground and the annular convex portion 211 is left, so that the subsequent handling of the protective cover wafer 2 is facilitated and less likely to be damaged. Possible

(4) Bonding Step After performing the protective cover wafer grinding step, the surface 20 which is the device forming surface of the device wafer 1 is made to face the surface 20 which is the groove forming surface of the protective cover wafer 2 as shown in FIG. Then, the notch 14 and the positioning mark 23 are aligned and bonded together with a bonding agent or the like. At this time, as shown in FIG. 4, the pair of grooves 22 a and 22 b are located at positions shifted from directly above the bonding pad 13 toward the center side of the device region 12.

(5) Bonding pad exposure step After performing the bonding step, the bonding pad 13 is exposed by cutting the protective cover wafer 2 constituting the bonded wafer 5 along the grooves 22a and 22b with a cutting blade.

  For example, as shown in FIG. 8, a cutting blade 31 having a relatively thin blade thickness is rotated at a high speed so as to be cut above the grooves 22a and 22b, whereby the end material 24 between the grooves 22a and 22b is formed. By removing, the through-hole 24a is formed and the bonding pad 13 is exposed.

  Thus, since the bonding pad 13 can be exposed from the protective cover 2 by cutting, it is not necessary to perform etching. Therefore, troublesomeness such as management of the etchant is eliminated.

(6) Dividing Step Before or after the bonding pad exposing step, the bonded wafer 5 is divided along the scheduled dividing line 11. For example, as shown in FIG. 9, a cutting blade 31 having a thin blade thickness is rotated at a high speed to be cut into the division schedule line 11 to form grooves 16 penetrating the front and back of the device wafer 1, thereby making each device 12 The device 15 with a protective cover is divided. Each device 15 with a protective cover formed in this manner is protected by the protective cover 25 with the bonding pad 13 exposed.

  In the protective cover wafer grinding step, since the concave portion 210 is formed on the back surface of the protective cover wafer 2 and the concave portion 210 is surrounded by the annular convex portion 211, the strength of the protective cover wafer can be increased. Even if the ratio of the through-holes 24a to 2 increases, the protective cover wafer 2 can be thinned. Therefore, the protective cover 25 constituting each device 15 with a protective cover can be made thinner than before, and the device 15 with a protective cover can be made thinner.

2 Second Embodiment (1) Device Wafer Preparation Step A device wafer 6 shown in FIG. 10 is prepared. The device wafer 6 is configured by forming devices 62 in a region defined by a plurality of intersecting division lines 61 on the surface 60, and on the surface 60, bonding pads are formed along each side of each rectangular device 62. 63 is formed. A notch 64 for crystal orientation identification is formed at the peripheral edge of the device wafer 6.

(2) Protection Cover Wafer Groove Processing Step In covering each device constituting the device wafer 6 with the protection cover, for example, a protection cover wafer 7 shown in FIG. 11 is manufactured. Grooves 72 for accommodating the bonding pads 63 are formed on the surface 70 of the protective cover wafer 7 vertically and horizontally. The groove 72 can be formed using a cutting blade in the same manner as in FIG. A positioning mark 73 is formed on the peripheral edge of the protective cover wafer 7 in a cutout state.

(3) Protective Cover Wafer Grinding Step Before or after the protective cover wafer groove machining step, the back surface 71 of the protective cover wafer 7 is ground as shown in FIG. As shown in the protective cover wafer 7 shown in FIG. 5, the concave portion 710 and the annular convex portion 711 are formed, and the concave portion 710 is surrounded by the annular convex portion 711.

(4) Bonding Step As shown in FIG. 13, the surface 70 of the protective cover wafer 7 is made to face the surface 60 of the device wafer 6 so that the groove 72 is located on the center side of the device 62 with respect to each bonding pad 63. Then, a bonded wafer 8 is formed. At the time of bonding, the notch 64 of the device wafer 6 and the positioning mark 73 of the protective cover wafer 7 are aligned.

(5) Bonding pad exposure step After the bonding step, as shown in FIG. 14, the protective cover wafer 7 constituting the bonded wafer 8 is cut along the groove 72 by the cutting blade 31 to thereby bond the bonding pad 63. To expose. By cutting the cutting blade 31 having a relatively thin blade thickness into the groove 72 and removing the end material 74 between the two grooves 72, a through hole 74a is formed and the bonding pad 63 is exposed.

  Thus, since the bonding pad 63 can be exposed from the protective cover 7 by cutting, it is not necessary to perform etching. Therefore, troublesomeness such as management of the etchant is eliminated.

(6) Dividing Step The bonded wafer 8 is divided along the scheduled dividing line 61 before or after the bonding pad exposing step. For example, as shown in FIG. 15, a cutting blade 31 that rotates at a high speed is cut into a division line 61 to form grooves 66 that penetrate the front and back of the device wafer 1, thereby providing a device with a protective cover for each device 62. Divide into 65. The protective cover-equipped device 65 thus formed is protected by the protective cover 75 with the bonding pads 63 exposed.

  In the protective cover wafer grinding step, since the concave portion 710 is formed on the back surface of the protective cover wafer 7 and the concave portion 710 is surrounded by the annular convex portion 711, the strength of the protective cover wafer 7 can be increased. Even if the ratio of the through holes 74a to the cover 7 is increased, the protective cover wafer 7 can be thinned. Therefore, the protective cover 75 constituting each device 65 with a protective cover can be made thinner than before, and the device 65 with a protective cover can be made thinner.

1: Device wafer 10: Surface 11: Planned division line 12: Device 13: Bonding pad 13a, 13b: Bonding pad row 14: Notch 15: Device with protective cover 16: Groove 2: Protective cover wafer 20: Surface 22a, 22b: Groove 21: Back 210: Concave 211: Annular convex 23: Positioning mark 24: End material 24a: Through hole 25: Protective cover 3: Cutting means 30: Spindle 31: Cutting blade 32: Nut 4: Grinding device 40: Holding table 41: Grinding means 410: Rotating shaft 411: Wheel 412: Grinding wheel 5: Bonded wafer 6: Device wafer 60: Surface 61: Line to be divided 62: Device 63: Bonding pad 64: Notch 65: Device with protective cover 66: Groove 7: protective cover wafer 7 0: front surface 72: groove 71: back surface 710: concave portion 711: annular convex portion 73: positioning mark 74: end material 74a: through hole 75: protective cover 8: bonded wafer

Claims (1)

A method of manufacturing a device with a protective cover, comprising:
A device wafer preparation step of preparing a device wafer in which a device including a bonding pad formed adjacent to the division line is formed in each region divided by a plurality of intersecting division lines;
A protective cover wafer groove processing step for forming a groove with a cutting blade in a region on the protective cover wafer corresponding to a region on the device central side adjacent to the bonding pad on the surface of the device wafer, and processing the protective cover wafer;
Before or after performing the protective cover wafer groove processing step, a protective cover wafer grinding step for forming a concave portion by grinding the center of the back surface of the protective cover wafer and forming an annular convex portion surrounding the concave portion;
The groove is caused to correspond to the device center side of the bonding pad of the device wafer, and the surface of the device wafer on which the device is formed is bonded to the surface of the protective cover on which the groove is formed. A bonding step to form a wafer;
A bonding pad exposing step of exposing the bonding pad by cutting the protective cover wafer of the bonded wafer along the groove with a cutting blade;
A division step of dividing the bonded wafer along the division line before or after the bonding pad exposing step.

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